1. Field of the Invention
This invention relates to easily dispersible pigments. More specifically, it relates to a process for rendering a high solids pigment presscake into a more fluid form by the addition of resins and to pigment dispersions prepared by this process.
2. Current Practice
In the preparation of inks, paints, colored plastics, and the like, it is essential that the pigment be uniformly dispersed in the vehicle. There are many techniques for improving dispersibility of pigments such as adding the pigment in the form of a fine powder. However, powdered pigments are difficult to redisperse to obtain maximum dispersion.
While pigment presscake disperses more readily in a water flexo ink than dry pigment powders, nevertheless, due to the low solids content of the aqueous cake generally obtained by conventional processes, dispersion of untreated presscake in water flexo inks is not economically feasible because of the low pigment loading. Methods for preparing high solids presscakes from the conventional presscake obtained from a filter press are known to those skilled in the art. Such high solids presscakes allow for high pigment loading and are readily dispersible in water flexo inks but are difficult to handle and particularly are not readily pumpable. Accordingly, it is desirable to be able to fluidize the high solids pigment presscake for ease of handling. Thus, it is a purpose of this invention to fluidize pigment presscakes for ease of handling and to achieve improved dispersion and excellent color properties.
______________________________________ Prior Patents of Interest U.S. Pat. No. Issued Inventor(s) Assignee ______________________________________ U.S. Pat. No. 4,036,652 7/19/77 Rothmayer Sun Chemical U.S. Pat. No. 3,945,843 3/23/76 Holty et al Nalco U.S. Pat. No. 4,230,610 10/28/80 Falcione et al Calgon European 0050313A1 4/28/82 Deubel et al Hoechst ______________________________________